US4706000A - Tool posture control system - Google Patents

Tool posture control system Download PDF

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Publication number
US4706000A
US4706000A US06/860,192 US86019286A US4706000A US 4706000 A US4706000 A US 4706000A US 86019286 A US86019286 A US 86019286A US 4706000 A US4706000 A US 4706000A
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US
United States
Prior art keywords
tool
vector
robot
coordinate system
searching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US06/860,192
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English (en)
Inventor
Hajimu Kishi
Shinsuke Sakakibara
Haruyuki Ishikawa
Yuuichi Kanda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fanuc Corp
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Fanuc Corp
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Publication date
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Assigned to FANUC LTD reassignment FANUC LTD ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ISHIKAWA, HARUYUKI, KANDA, YUUICHI, KISHI, HAJIMU, SAKAKIBARA, SHINSUKE
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Publication of US4706000A publication Critical patent/US4706000A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1679—Programme controls characterised by the tasks executed
    • B25J9/1692—Calibration of manipulator
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/41—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/45—Nc applications
    • G05B2219/45104—Lasrobot, welding robot
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/49—Nc machine tool, till multiple
    • G05B2219/49386—Automatic seam, weld line, finding
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/50—Machine tool, machine tool null till machine tool work handling
    • G05B2219/50353—Tool, probe inclination, orientation to surface, posture, attitude

Definitions

  • the present invention relates to a tool posture control system, and more particularly to a system for controlling the posture of a tool while searching for an arc starting point by controlling the posture vector of the searching posture of the tool using a tool coordinate system, and by tilting the tool in a certain direction in a searching coordinate space for thereby seaching for the arc starting point.
  • FIG. 4 of the accompanying drawings shows a general welding robot.
  • the illustrated welding robot is an articulated robot having six axes. These six axes include a T( ⁇ )-axis about which an arm assembly rotates, a W-axis about which a lower arm is tilted back and forth, a U-axis about which an upper arm is tilted vertically, an A-axis about which a wrist rotates in a horizontal plane, a B-axis about which the wrist moves in a vertical plane, and a C(r)-axis about which the wrist rolls, these axes being independently controlled.
  • Designated at 1 in FIG. 4 is a base on which the articulated robot is supported.
  • a T( ⁇ )-axis servo motor 2 is mounted in the base 1 for turning the axes about the vertical axis (Z-axis).
  • a W-axis unit 4 is fixedly mounted on the T( ⁇ )-axis unit 3, and a W-axis arm 5 is rotatably supported by a pivot shaft 5a on the W-axis unit 4, the W-axis arm 5 being operated by a W-axis drive mechanism 6.
  • a U-axis arm 7 is rotatably supported by a pivot shaft 7a on the distal end of the W-axis arm 5, the U-axis arm 7 being operated by a U-axis drive mechanism 8.
  • a wrist mechanism 9 is mounted on the distal end of the U-axis arm 7. The wrist mechanism 9 is rotated by an A-axis servo motor 10, vertically swung by a B-axis servo motor 11, and rolled by a C-axis servo motor 12. Robot operation is performed by a tool attached to the wrist mechanism 9. A torch used as such a tool and an arc welding process employing the torch will be described.
  • FIG. 5 schematically shows an arc welding machine.
  • a wire WR is fed by rollers FR in small increments in the direction of the arrow, and passes through a guide member GB to project from the distal end of a torch TC.
  • the rate of feed of the wire WR is limited such that the distal end of the wire will be spaced a prescribed distance from the surface of a member WK to be welded.
  • the positive potential of a high voltage which is generated by a welding power supply PS intermittently with a given period is applied to the wire WR through the guide member GB, whereas a negative potential is impressed on the member WK to be welded.
  • a gas is supplied from a gas supply (not shown) in the direction of the arrows through the torch TC and applied to the member WK to prevent a welded area from being oxidized.
  • the torch is moved with respect to the member to be welded to search for an arc starting point while manually searching for the position of the member to be welded.
  • FIG. 6 is a diagram explanatory of such robot, hand, and tool coordinate systems.
  • the robot reference coordinate system is indicated by x, y, z with O denoting the origin.
  • Designated at l, m, n are hand posture vectors in the robot hand coordinate system, while designated at t, u, v are tool posture vectors in the tool coordinate system.
  • Denoted at TCP is a tool center point (also referred to as a tool grip point).
  • a tool posture control system has a robot having an arm, a tool mounted on the distal end of the arm, principal vector setting means for determining the principal position of the robot, means for determining a tool vector indicative of the present position of the tool, means for determining a target tool vector inclined with respect to the principal vector, rotating means for rotating the tool vector indicative of the present position of the tool to the target tool vector through vector rotation, means for generating data for driving the axes of the robot from data produced by rotating the tool vector indicating the present position with the rotating means, and for moving the tool to the position of the target tool vector.
  • the torch as the tool can automatically be set to a position having the best inclination when it is initially established. Since an arc starting point can thus be searched for accurately, the desired operation for searching for the arc starting point can properly be performed without human intervention.
  • FIG. 1 is a diagram explaining the manner in which a tool posture vector is controlled in a searching coordinate space
  • FIG. 2 is a flowchart of operation of means for controlling the tool posture vector
  • FIG. 3 is a view showing an example to which a process of controlling the tool posture vector is applied
  • FIG. 4 is a view of a general welding robot
  • FIG. 5 is a schematic view of an arc welding machine
  • FIG. 6 is a diagram explaining a robot coordinate system and a tool coordinate system.
  • FIG. 1 is explanatory of the control of the tool posture vector of a torch in a searching coordinate space, i.e., a coordinate space with a member to be welded being used as a reference, where the underlining of a letter indicates a vector.
  • FIG. 2 is a flowchart of the control sequence. Principal vectors in the searching coordinate space are indicated as d (x direction), a (y direction), and h (-z direction). Designated at t, u, v principal vectors in the tool coordinate space.
  • Searching posture directions for the tool are determined by angles between the principal vectors d, a, h in the searching coordinate space and the three fundamental t, u, v.
  • a present tool vector v is first determined.
  • a target tool vector v' is established with respect to each of the principal vectors d, a, h in the searching coordinate space.
  • the target tool vector v' is determined with respect to the vector -d which is one of the principal vectors in the searching coordinate space.
  • This tool vector v' is inclined ⁇ from the principal vector -d, the angle ⁇ being preset to an optimum value.
  • the target tool vector is determined with respect to the vector a that is one of the principal vectors in the searching coordinate space.
  • the target tool vector is determined with respect to the vector h that is one of the principal vectors in the searching coordinate space.
  • the present tool vector v 1 When transforming the present tool vector v 1 into the searching coordinate system, the present tool vector v 1 is rotated to the target tool vector v'. This is expressed by:
  • the present tool vector v 1 has thus been transformed into the searching coordinate system, and a tool posture vector is now obtained.
  • the transformed tool posture vector is then transformed to a robot hand posture vector, i.e., can be transformed to robot axis data. More specifically, normal and inverse transformation can be possible at all times between the hand posture vectors l, m, n and the fundamental axes t, u, v in the tool coordinate system. This is because the hand coordinate system and the tool coordinate system are always in fixed relative spatial positions, and hence the following equations can be established through one 3 ⁇ 3 fixed matrix (M): ##EQU1##
  • the torch serving as the tool can approach a given searching surface at a desired angle, with the result that an accurate arc starting point can be searched for.
  • FIG. 3 is a view illustrative of such control of the searching posture of the torch.
  • the torch (distal end of the wire) TC as the tool is located at the position ⁇ 1 and inclined at any angle.
  • the above-described tool posture control is effected in this position to cause the torch TC to be inclined at ⁇ 1 with respect to a line perpendicular to a side surface ⁇ a . From this position , the torch TC moves in a searching manner toward the side surface ⁇ a of a vertical plate of the L-shaped member until the torch TC contacts the side surface a at a position ⁇ 2 .
  • the torch TC returns to the initial position ⁇ 1 , wherein the torch posture control is carried out to direct the torch TC to be inclined at ⁇ 2 with respect to the upper surface ⁇ b of a horizontal plate of the L-shaped member. Thereafter, the torch TC is lowered until it contacts the upper surface b at a position ⁇ 3 . In the position ⁇ 3 , the torch TC is controlled in its posture again so to be inclined at ⁇ 3 , and then the torch TC is moved in a searching manner toward a side edge of the horizontal plate of the L-shaped member. When the torch TC reaches the edge ⁇ 4 , the foregoing torch posture control is performed again to move the torch TC toward an arc starting point S.
  • the present invention is not limited to welding robot applications, but may suitably be employed for controlling the posture of other articulated robots.

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  • Engineering & Computer Science (AREA)
  • Computing Systems (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Robotics (AREA)
  • Mechanical Engineering (AREA)
  • Manipulator (AREA)
  • Numerical Control (AREA)
US06/860,192 1984-08-24 1985-08-21 Tool posture control system Expired - Fee Related US4706000A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP59-175154 1984-08-24
JP59175154A JPS6154506A (ja) 1984-08-24 1984-08-24 ア−ク開始点探索時のツ−ルの探索姿勢制御方式

Publications (1)

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US4706000A true US4706000A (en) 1987-11-10

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US06/860,192 Expired - Fee Related US4706000A (en) 1984-08-24 1985-08-21 Tool posture control system

Country Status (4)

Country Link
US (1) US4706000A (fr)
EP (1) EP0194314A4 (fr)
JP (1) JPS6154506A (fr)
WO (1) WO1986001617A1 (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4853603A (en) * 1987-03-19 1989-08-01 Kawasaki Jukogyo Kabushiki Kaisha Control of an industrial robot
US4899095A (en) * 1985-06-25 1990-02-06 Fanuc Ltd Robot control system
US4954762A (en) * 1989-02-01 1990-09-04 Hitachi, Ltd Method and apparatus for controlling tracking path of working point of industrial robot
US4972347A (en) * 1988-10-11 1990-11-20 Cincinnati Milacron Inc. Method and apparatus for determining the correct tool dimensions for a three dimensional tool mounted on a manipulator
US5132601A (en) * 1988-12-02 1992-07-21 Tokico Ltd. Industrial robot
US5194792A (en) * 1989-03-31 1993-03-16 Fanuc Ltd. Tool center point setting method in a robot
US5789890A (en) * 1996-03-22 1998-08-04 Genmark Automation Robot having multiple degrees of freedom
US6121743A (en) * 1996-03-22 2000-09-19 Genmark Automation, Inc. Dual robotic arm end effectors having independent yaw motion
US6192298B1 (en) * 1997-05-30 2001-02-20 Matsushita Electric Industrial Co., Ltd. Method of correcting shift of working position in robot manipulation system
US6489741B1 (en) 1998-08-25 2002-12-03 Genmark Automation, Inc. Robot motion compensation system
US20150015781A1 (en) * 2006-01-31 2015-01-15 Andrew Flessas Robotically controlled video projectors
US20180311823A1 (en) * 2015-10-29 2018-11-01 Airbus Sas Method for orienting an effector carrying an assembly tool relative to a surface
US11284048B2 (en) 2006-01-31 2022-03-22 Andrew Flessas Robotically controlled display
US11350064B2 (en) 2019-08-29 2022-05-31 Andrew Flessas Method and system for moving cameras using robotic mounts
US11425308B2 (en) 2020-12-02 2022-08-23 Andrew Flessas Robotically movable display synchronously movable with robotically movable camera for displaying captured images in identical orientation

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08383B2 (ja) * 1987-08-04 1996-01-10 株式会社明電舎 ロボットの制御装置
JP2012228760A (ja) * 2011-04-27 2012-11-22 Yaskawa Electric Corp ロボット
JP5545263B2 (ja) * 2011-04-27 2014-07-09 株式会社安川電機 ロボットシステム及び被作業物の製造方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4528632A (en) * 1981-03-18 1985-07-09 Kabushiki Kaisha Yaskawa Denki Seisakusho Industrial articulated robot linear interpolation control device
US4575802A (en) * 1983-07-11 1986-03-11 United Technologies Corporation Robot/workpiece orientation

Family Cites Families (4)

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Publication number Priority date Publication date Assignee Title
US4249062A (en) * 1978-03-09 1981-02-03 Shin Meiwa Industry Co., Ltd. Apparatus and method for sensing welding point in automatic welding apparatus
JPS5775309A (en) * 1980-10-29 1982-05-11 Fanuc Ltd Numerical control system
JPS5783390A (en) * 1980-11-07 1982-05-25 Hitachi Ltd Indirect instruction method for articulated type robot
JPS59144575A (ja) * 1983-02-04 1984-08-18 Mitsubishi Heavy Ind Ltd 溶接マニプレ−タ−の三次元数値制御方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4528632A (en) * 1981-03-18 1985-07-09 Kabushiki Kaisha Yaskawa Denki Seisakusho Industrial articulated robot linear interpolation control device
US4575802A (en) * 1983-07-11 1986-03-11 United Technologies Corporation Robot/workpiece orientation

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"Classical Mechanics" Herbert Goldstein, Addison-Wesley Publishing Co. 1950, pp. 97-101.
Classical Mechanics Herbert Goldstein, Addison Wesley Publishing Co. 1950, pp. 97 101. *

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4899095A (en) * 1985-06-25 1990-02-06 Fanuc Ltd Robot control system
US4853603A (en) * 1987-03-19 1989-08-01 Kawasaki Jukogyo Kabushiki Kaisha Control of an industrial robot
US4972347A (en) * 1988-10-11 1990-11-20 Cincinnati Milacron Inc. Method and apparatus for determining the correct tool dimensions for a three dimensional tool mounted on a manipulator
US5132601A (en) * 1988-12-02 1992-07-21 Tokico Ltd. Industrial robot
US4954762A (en) * 1989-02-01 1990-09-04 Hitachi, Ltd Method and apparatus for controlling tracking path of working point of industrial robot
US5194792A (en) * 1989-03-31 1993-03-16 Fanuc Ltd. Tool center point setting method in a robot
US6121743A (en) * 1996-03-22 2000-09-19 Genmark Automation, Inc. Dual robotic arm end effectors having independent yaw motion
US6037733A (en) * 1996-03-22 2000-03-14 Genmark Automation Robot having multiple degrees of freedom
US5789890A (en) * 1996-03-22 1998-08-04 Genmark Automation Robot having multiple degrees of freedom
US6192298B1 (en) * 1997-05-30 2001-02-20 Matsushita Electric Industrial Co., Ltd. Method of correcting shift of working position in robot manipulation system
US6489741B1 (en) 1998-08-25 2002-12-03 Genmark Automation, Inc. Robot motion compensation system
US20150015781A1 (en) * 2006-01-31 2015-01-15 Andrew Flessas Robotically controlled video projectors
US9497431B2 (en) * 2006-01-31 2016-11-15 Andrew Flessas Robotically controlled video projectors
US11284048B2 (en) 2006-01-31 2022-03-22 Andrew Flessas Robotically controlled display
US11683456B2 (en) 2006-01-31 2023-06-20 Andrew Flessas Robotically controlled display
US20180311823A1 (en) * 2015-10-29 2018-11-01 Airbus Sas Method for orienting an effector carrying an assembly tool relative to a surface
US11350064B2 (en) 2019-08-29 2022-05-31 Andrew Flessas Method and system for moving cameras using robotic mounts
US11425308B2 (en) 2020-12-02 2022-08-23 Andrew Flessas Robotically movable display synchronously movable with robotically movable camera for displaying captured images in identical orientation

Also Published As

Publication number Publication date
EP0194314A1 (fr) 1986-09-17
EP0194314A4 (fr) 1989-04-24
WO1986001617A1 (fr) 1986-03-13
JPS6154506A (ja) 1986-03-18

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